This is a device used to convert the light energy into electrical energy.
Under the reverse bias condition, if the light ray is incident over the intrinsic region, then it will produce the electron hole pair.
The accelerated electron-hole pair charges carrier produce the photo-current.
It consists of three layerssuch as p, n and intrinsic region with proper biasing.
The P and N region are heavily doped.
The intrinsic layer is slightly larger than both the p-type and n-type for receive the light photons.
The PIN diode is heavily reverse biased.
When a photon of higher energy is incident over the larger width intrinsic semiconductor layer, then the electron hole pairs are created.
The mobile charges are accelerated by the applied voltage, which gives rise to photo current in the external circuit.
It is a linear device because the photo-current is directly proportional to the incident optical power on the PIN photo-diode.